Machining of wood : cutting data and its effect on the work environment and surface quality

Abstract: Machining using circular tools is very frequent in the wood manufacturing industry. Such machinery is very efficient but also leads to problems, for example in the indoor factory environment, in the form of unhealthy wood dust emissions. Another example is imperfections in wood products such as unacceptable surface quality. In order to tackle these problems it has been necessary to study the cutting process in detail. By attaching a load cell to the work piece and other measuring devices it has been possible to study the cutting operation during the relevant machining conditions.Much research has previously been done on wood machining, from the 1930's and onwards. However, the research done on peripheral milling, which is the machining method of the industry, is scarce. The objective of this work is to gather knowledge to be able to minimize the defects created by the milling or planing operations and also to find ways of lowering the dust emitted during wood machining. The hypothesis for this work has been that the choice of cutting data and tool geometries will have an influence on both wood defects as well as dust. The experiments made have focused on finding relationships between the cutting data, which is chosen in each machining case, and the wood defects and dust emission. When studying surface defects, a theory concerning cutting forces and their cause of wood defects has been formulated. To be able to measure and analyze the cutting forces, it was necessary to find a method for this, which is described in one of the articles.The result of the experiments, described in the articles, show that it is certainly possible to reduce the amount of dust emitted from a machining operation by choosing cutting data in a specific way. The result shows that it is important to choose data, which will give an average chip thickness above 0.1 mm, to prevent the dust emitted increasing dramatically. It is also shown that some wood materials create more dust than others. When studying the defects, it is essential to know how the chosen cutting data and tool geometries effect the direction and magnitude of the cutting force. In the second article a method for evaluating the cutting force is presented and in the third article it is shown how different cutting data creates different cutting forces. Knowing these correlations makes it possible to reduce certain unwanted surface defects.This thesis shows that there is a potential in measuring the cutting force in order to be able to avoid certain defects. Much more work has still to be done to be able to find out how all combinations of cutting data and tool geometries affect this.